Education and training programs for radiation therapy technology, dosimetry, medical physics and radiation oncology teach the basic principles of radiation therapy in the classroom and depend on student access to computer-based treatment planning (RTP) systems for hands-on practice to solidify the principles taught in the classroom and to develop planning skills. Major shortcomings and problems facing programs include limited access to clinical RTP systems;inflexibility of commercial RTP systems to meet education/training needs;the absence of a model curriculum for computer-based training;and the lack of computer-based learning materials specifically structured to meet the needs of RTP education and training. The overall goal is to provide resources to improve instruction of the principles and practice of dosimetric planning for external beam radiation treatment in education and training programs. The proposed work is aimed primarily at radiation therapy technology and dosimetry programs, but also will be valuable for medical physics and radiation oncology programs.